I have read something about connecting a cd-rom to those machines but I have some questions.
I have a NEC scsi cd-rom;
Is there any way to buy an adapter or external case to connect it to the rear of the mac?
I supoose I will need some kind of driver.
Is there any way to connect this cd-rom internaly to the same wire of the HD?
In the case that this is factible does anyone know where to buy a a slot load cdrom?
Thankyou
Joan
Yes. External SCSI cases were made just for this purpose. Check eBay, or ask the friendly folks here at the Fritter.
CD-ROM Toolkit was a program that was available in the ol' System 7 days, and did a great job then of making CD-ROMs work with Macs -- even better than Apple's own CD-ROM driver.
Unfortunately, after searching for the last 30 minutes for any sign of CD-ROM Toolkit or its publisher, FWB Software, I've hit a brick wall. Again, maybe a fellow 'Fritterian has a copy lying around.
Not likely in a Classic, Color Classic or their "II" offspring. Not enough room inside.
Not a SCSI slotloader. At least not that I've ever seen.
I believe it was System 7.6 CD-ROM drivers that worked out of the box with generic drives.
There's also a patch around:
http://www.heise.de/ct/english/98/26/188/
I've got FWB's Hard disk toolkit, which has thus far done a good job of mounting other obscure SCSI stuff... think that would do the trick?
Just to clarify - I actually own a SCSI slot-loading CD-ROM drive that I found (if memory serves) on eBay a few years back. It's been waiting for me to get off my butt and hack it into a compact Mac. I just thought it was worth mentioning that, while rare, SCSI slot-loaders do exist.
Huxley
Finally I have managed to put 2 hard disks to the color classic.
What I have done is to put the two drives provisionally at the back of the computer using a long 50 pins scsi cable I have modified.
Now I want to try it with one HD and one CD-ROM.
As a newbee in classic macs I have some questions.
First are relative to SCSI jumpers, id's, and terminations.
Can someone tell me the exact way to connect de HD and the cd-rom.
Do I have to attach first de hd or the cd-rom or it's indifferent?
The HD has 5 jumpers and are labelled:
PK
TE
A0
A1
A2
What's the meaning of those words.
The cd-rom (a NEC CDR-1910A) has 6 jumpers blocks
::::::
and by default it comes with jumper 1-3-5 closed
[]:[]:[]:
I have found an excellent page that goes into detail about the jumpers.
http://support.dell.com/support/edocs/storage/NEC1910A/Jumpers.htm
Does system 7.1 support cd-rom drives?
Where do I have to put the drivers?
Thankyou
Gus
You simply have to put the driver into the Extensions folder.
(I have discovered where to put the driver)
Gus
PK - probably park, you dont want a jumper here
TE - Termination... never entirely figured out scsi termination... if it doesn't work one way, try the other.
A2, A1, A0 - ID bits. A SCSI chain can have 7 devices connected, but they all have to have a different ID; because 111 in binary is 7 in base-ten, those A# jumpers are binary digits.
000 = 0
001 = 1
010 = 2
011 = 3
100 = 4
and so on. You use a combination of jumpers to specify the SCSI id, where a "1" would HAVE a jumper, and a "0" wouldn't.
I thought scsi drives weren't supposed to NEED drivers. Am I not right?
BTW, this is drives, not peripherals
I think HD's don't need drivers but cd-roms need.
I think at least one drive has to be TE - termination.
It's something relative to the signal that starts bouncing by the scsi cable causing noise and possible errors in the data being transferred if any drive has TE - termination.
Gus
I read a lot those days 
Finally I will reply all my questions
Terminations has to be at both ends of the chain.
Said you have a card with an internal and external port
You need the terminate the drive (or cable) at the end, and the card if the internal is only used. Same goes for the external only
If the internal AND external are used. You need to terminate the drive at the end of the internal, and then the end of the external (but not the card). This is assuming that both of the chains are connected (i.e. there aren't two scsi busses on the card)
In this case, if the computer has a termination at the board (Logic Board) that does auto, then the drive (or connector) at the end of the internal cable needs a terminator. the board will term itself. If you use both the internal and the external, and the board DOESN'T have termnation at the board, you need to terminate the end of the internal, and at the end of the external
if you use the internal only, the board should terminate itself.
Termination cancels the echo at the end of the cable from bouncing back. Think of it as a noise black-hole. Completely cuts the echo that bounces off the end of the cable and comes back to the controller.
This is generally done using resisters.
I have only come across a few CD-ROMS that needed SCSI Drivers. I had an HP CD-RW (4x4x8) internal drive, that needed to have drivers to burn (patchburn for OS 9) but never had to have drivers to read. One thing I DO know, is if you start up off of it (like have a bootable Zip/CD/Jaz) it won't need a Driver to start up off of it.